1. Field of the Invention
The present invention relates to a linear vibrator. A linear vibrator is an apparatus having a vibrating unit which generates a vibration by a reciprocating motion.
2. Description of the Related Art
A related art linear vibrator is provided in a circular shape. The linear vibrator includes a circular case, a coil mounted at the bottom surface of the circular case, a circular vibrating unit contained inside of the circular case, a magnet fixed at the circular vibrating unit, and a spring appending the vibrating unit to the circular case. As for the operation of the vibrator, if an electric power is supplied to the coil, the vibrating unit oscillates up and down by an electromagnetic force generated between the coil and the magnet.
However, the related art circular vibrator has a difficulty being miniaturized. More particularly, the related art circular vibrator is formed in a circular shape. Because the circular vibrator and other components are installed together in a communication apparatus, there exist useless spaces between the external face of the related art vibrator and the external faces of the other components. Thus, there is a limitation in miniaturizing a communication apparatus employing the related art circular vibrator, which has a difficulty in miniaturization. It has been considered to replace the circular vibrator case with a hexahedron case having a square shaped section to solve this problem. However, it is difficult to arrange circular components such as a circular vibrating unit in a square shaped case.
There has previously been presented a linear vibrator consisting of a square shaped case and square shaped components to solve a problem caused by providing the vibrator in a circular shape. A related art square shaped vibrator includes a pair of magnets stacked in both the upper and the lower end parts of the case, and a coil located in the internal space of the case and appended to the case by a spring. In operation, if electric power is supplied to the coil, an electromagnetic force generates a vibration.
However, since the related art vibrator has a pair of magnets respectively positioned at both end parts of a square shaped case, the related art vibrator requires four magnets. Since the related art linear vibrator requires many magnets, which can be expensive, the production cost of the linear vibrator increases.
Furthermore, since the related art vibrator has a structure in which the coil itself vibrates up and down, a load can be applied to the coil. As a result, there is a problem in that the repeated load may be transmitted to an outlet line which is connected in the coil, so that the outlet line can be cut. Therefore, there is a shortcoming that may decrease the reliability of the product.
Moreover, there is an action that reduces a magnetic flux connected from the pair of magnets stacked up and down with mutually-crossing polarity to the coil. More particularly, a flux extending from one of the magnets to the coil should be horizontally directed to the coil, but there is a problem in that the flux may be pulled into the other magnet and be extinguished. Therefore, there may occur a reduction of the magnetic flux density in the horizontal direction, resulting in a reduction of the electromagnetic force generated between the coil and a magnet and a reduction of the vibration quantity. Accordingly, there may be a delay of time interval until the normal vibrating quantity is reached.